1. Field of the Invention
This invention relates to a device for draining ground areas, particularly for draining sandy ground areas, such as tennis-courts, sand-tracks and the like.
2. Description of the Prior Art
A device of the above-mentioned type has already been described in GB-PS 1 033 500 and comprises a perforated hollow metal roller mounted on a chassis and adapted to roll on the ground to be drained. The chassis carries a water tank, which is first linked to a suction pump and second to a suction nozzle arranged within the metal roller and immediately above that portion of the roller which is in contact with the ground. During operation, the water entering into the metal roller through the perforations is sucked up by the suction nozzle and conveyed into the water tank.
The range of application of such device is very limited, and such can be employed only for draining ground areas which have solid surfaces or which are covered by grass. This is due to the fact that, when draining sandy ground areas, components thereof enter into the metal roller together with the water. Such sand components are then sucked up by the suction nozzle and conveyed into the water tank. The air speed in the nozzle must be relatively high, which creates a further adverse effect in such prior art device.
For draining sandy ground areas, it is further known to employ rollers which are covered by sponges, the water which is sucked up by the sponge being squeezed into a basin by means of a squeezing roller arranged on the rear side of the roller with respect to the moving direction. This device also has the disadvantage that the sand which has been removed from the ground and which sticks to the surface of the sponge roller is also conveyed into the basin. This is a particularly adverse situation, since still further layers of sand will be removed from those regions of the ground surface on which puddles have been formed because of cavities.